Image display devices are used to display both still images and moving video images, which are generated by or stored locally within the image display device or received from an external source device. A still or video frame image will herein be referred to collectively as an image. Typically, the image display device displays the image or series of images within an image display window, which takes up either all or a portion of the display area of the image display device. An image display device can include one or more image display windows in which images are displayed.
Image display devices include both televisions and personal computer (PC) monitors. Existing televisions and PC monitors are different. Televisions generally have a medium display resolution capability and several analog interfaces for receiving input signals, such as a composite video interface, an s-video interface and a radio frequency interface for radio frequency signals received over coaxial cable. Although, televisions are advancing in their ability to display increasingly higher resolutions of video and graphic data, consumer video resolution has changed little over time. While the picture tube of PC monitors is based on consumer television technology, PC monitors or displays have different resolution requirements than consumer televisions, due to the need for PC monitors to have the ability to display legible small text and fine lines for detailed work. To meet this need, PC monitors have a higher resolution than consumer televisions and very different high bandwidth interfaces, such as Video Graphics Array (VGA), Super VGA (SVGA) and RGB. In most modern computer systems an operating system provides a graphical interfac for the computer user. The user can run application programs, manipulate files, and perform most other necessary functions through this graphical interface by manipulating images on the computer's display. This manipulation is accomplished by using cursor control keys and other keyboard keys or by using a cursor controlling peripheral device such as a joystick, mouse or trackball.
A schematic block diagram of a typical configuration including an external image source 10 and a host computer system 20 is illustrated in FIG. 1. The external image source 10 is coupled to an interface port 28 of the computer system 20 by a bus or cable for transmitting image or video data to the computer system 20 for display. The host computer system 20, illustrated in FIG. 1, is exemplary only and includes a central processor unit (CPU) 42, a main memory 30, a video display adapter 22 such as a graphics adapter (VGA) card, a mass storage device 32 and an interface circuit 28, all coupled together by a conventional bidirectional system bus 34. The mass storage device 32 may include both fixed and removable media using any one or more of magnetic, optical or magneto-optical storage technology or any other available mass storage technology. The system bus 34 contains an address bus for addressing any portion of the memory 30. The system bus 34 also includes a data bus for transferring data between and among the CPU 42, the main memory 30, the display adapter 22, the mass storage device 32 and the interface circuit 28.
The host computer system 20 is also coupled to a number of peripheral input and output devices including the keyboard 38, the mouse 40 and the associated display 36. The keyboard 38 is coupled to the computer system via a keyboard/mouse interface 46 for allowing a user to input data and control commands into the computer system 20. A conventional mouse 40 is coupled to the keyboard 38 for manipulating graphic images on the display 36 as a cursor control device. Alternatively, as is known in the art, the mouse 40 is coupled directly to the computer system 20 through a serial port.
The display adapter 22 interfaces between the components within the computer system 20 and the display 36. The display adapter 22 converts data received from the components within the computer system 20 into signals which are used by the display 36 to generate images for display in one or more image display windows.
To control the display of a single image or a stream of images, such as a video stream, on an image display device, such as the display 36, a user typically has to manually change control parameters of the image display device or particular image display window, such as resolution or magnification, either on the display device 36, or within the application program providing the image to be displayed or operating the image display window. Another conventional method of changing parameters such as resolution or magnification is to use zoom control features to zoom in or zoom out on the image itself. However, when using such zoom control features, and the image is magnified to be bigger than the display window, the user then also has to use separate positional controls on the edge of the display window to display different portions of the image. There is currently a lack of image display devices which allow easy control of display parameters such as zoom and magnification to control the display of an image within an image display window.